[PATCH 0/2] MR3735: user32/tests: Wait for GetMessage call to complete.

[Esme Povirk (＠madewokherd)]

It's possible otherwise for the second message to be sent before
GetMessage removes a posted message from the queue, in which case
GetMessage processes both sent messages.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=54407